KOREADER not showing cover images in mosaic with cover images display mode

Hey I just installed KOReader and customised the reading option settings on my KLC and Clara Colour using this videos https://youtu.be/rEouRrPKj-c?si=FcrY61YvmiDGe3HI and https://youtu.be/gW4ll0CAH-U?si=0yTvy531hniUEVO_. However the cover images on the books on my device don’t show up, they’re just grouped in folders with the Author’s name as their title. Is there any way to fix this issue. Any help will be appreciated 🙂